Suppression of phosphorus diffusion by carbon co-implantation

The impact of Si interstitial (Si _i) flux suppression on the formation of P junctions by rapid thermal annealing (RTA) is demonstrated. Here we investigate the role of amorphization coupled with C co-implantation on P diffusion and its activation. From experiments on C co-implants in a-Si versus c-Si, we conclude that only a small fraction of C interacts with Si interstitials (Si _i). We have demonstrated that optimization of implants followed by spike RTA yields extensions suitable for gate lengths of 30 nm, with vertical depth X _j=20 nm (taken at 5×10 ¹⁸ at./cm ³), abruptness of 3 nm/decade, and R _s=326 Ω/□.